Man-made chemicals are an integral and vital part of our modern lifestyles. They are found in a vast range of consumer products – from furniture, clothing and toiletries to electrical appliances, car interiors, food packaging and cleaning products. While many have undoubtedly improved the quality of our lives, some possess undesirable properties.
Studies have shown the adverse impacts of man-made chemicals on wildlife species. Now scientific evidence is growing about the possible links between certain chemicals, particularly hormone disrupting chemicals (or EDCs), and human health impacts such as cancer, reproductive problems, birth defects, asthma, allergies, behavioural problems, disruption of infant brain development, cardiovascular disease, diabetes, and obesity.
Humans are exposed to both industrial man-made chemicals and pesticides, through the food chain and from the vast array of consumer products in society. Wildlife, too, are exposed to the same chemicals via, for example, factory discharges, sewage effluents, leaking landfills and pesticides sprayed on the land.
More and more research scientists are becoming concerned that harmful chemicals are beginning to affect our health. We are exposed to a cocktail of many chemicals all the time and worries are now being expressed as to how this mixture may affect our health. Another major concern is exposure to chemicals whilst developing in-utero and how they may cause disease in later life. Diseases that we now think may be linked to exposure to certain chemicals include some cancers, reproductive problems, birth defects, asthma, allergies, behavioural problems, disruption of infant brain development, cardiovascular disease, diabetes and obesity.
Concern about the effects of man-made chemicals in humans, such as the decline in sperm counts, and the increases in certain diseases like some cancers, should lead to more precautionary regulation of chemicals.
Persistent and bioaccumulative chemicals
Many chemicals can persist in the environment and bioaccumulate in the bodies of wildlife and people. These properties have resulted in ecosystems all over the world being contaminated with a cocktail of man-made chemicals. Examples include the chemicals DDT (an insecticide) and PCBs (polychlorinated biphenyls – used in electrical components), which despite having been banned for decades, are still found throughout the global environment, including in our own bodies.
In more recent years, modern chemical compounds, still in use today, such as brominated flame retardants (used to prevent fire in plastics e.g. TVs, computers and textiles e.g. furniture, carpets) and perfluorinated “non-stick” chemicals, (used for waterproof and stain-proof coatings) have followed PCBs and DDT to all corners of the globe.
Hormone disrupting chemicals
Some chemicals can also interfere with hormone processes in the body – these are known as hormone disruptors or “endocrine disrupting chemicals” (EDCs). Examples include phthalates, used to make hard plastics soft and found in numerous consumer products, from vinyl flooring, shower curtains and toys to cosmetics.
Many chemicals with hormone disrupting properties have been detected in young children as well as adults, and in some cases at higher levels in children than in adults.
The History of the Concern about endocrine disrupting chemicals
In the early 1990s concern about the effects of chemicals escalated as research showed that many man-made substances, called endocrine disruptors or EDCs, could mimic or disrupt the action of hormones.In 1991, Theo Colborn, scientific researcher and co-author of Our Stolen Future, gathered a group of scientists together, and in 1992 the famous Wingspread consensus statement on hormone disruptors was published. This alerted the world with its prediction that “Unless the environmental load of synthetic hormone disruptors is abated and controlled, large scale dysfunction at the population level is possible”.
These scientists listed many wildlife populations that were already affected by hormone disruptors, and that the impacts included:
- thyroid dysfunction in birds and fish;
- decreased fertility in birds, fish, shellfish and mammals;
- decreased hatching success in birds, fish and turtles;
- gross birth deformities in birds, fish and turtles;
- metabolic abnormalities in birds, fish and mammals;
- behavioural abnormalities in birds;
- de-masculinisation and feminisation of male fish, birds and mammals;
- de-feminisation and masculinisation of female fish and birds;
- and compromised immune systems in birds and mammals.
The connection between effects in wildlife and the likely effects humans were also noted.
In the early days, industry appeared to try and play down the issue. Now the concern of the public and of scientists working in the field is ever increasing.